Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W48/00—Access restriction; Network selection; Access point selection
  • H04W48/20—Selecting an access point
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W36/00—Hand-off or reselection arrangements
  • H04W36/08—Reselecting an access point
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W74/00—Wireless channel access
  • H04W74/08—Non-scheduled access, e.g. ALOHA
  • H04W74/0833—Random access procedures, e.g. with 4-step access
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W74/00—Wireless channel access
  • H04W74/08—Non-scheduled access, e.g. ALOHA

Definitions

• the present invention relates inter alia to a method for an improved cell selection and/or cell reselection handling by an user equipment that is trying to camp on a radio cell of a public land mobile network, the improved cell selection and/or cell reselection handling being related to an uplink access procedure in dependency of attempts, by the user equipment, to get connected with the public land mobile network using a random access channel of the first base station entity and/or of the second base station entity.
• the present invention relates to a public land mobile network or telecommunications network for an improved cell selection and/or cell reselection handling by an user equipment that is trying to camp on a radio cell of a public land mobile network, the improved cell selection and/or cell reselection handling being related to an uplink access procedure in dependency of attempts, by the user equipment, to get connected with the public land mobile network using a random access channel of the first base station entity and/or of the second base station entity.
• the present invention relates to an user equipment for an improved cell selection and/or cell reselection handling in case that the user equipment tries to camp on a radio cell of a public land mobile network, the improved cell selection and/or cell reselection handling being related to an uplink access procedure in dependency of attempts, by the user equipment, to get connected with the public land mobile network using a random access channel of the first base station entity and/or of the second base station entity.
• RACH random access channel
• - sufficient downlink field-strengths can be measured from different cells of the same or different radio access technologies (RATs) or from the same or different frequency bands than the targeted radio cell (i.e. all these different radio cells (or the corresponding radio signals received by the user equipment) fulfill the so-called S-criterion and hence allow the user equipment to camp on such cells),
• RATs radio access technologies
• the uplink-access procedure (typically using the random access channel, RACH) to the selected serving cell (i.e. the one radio cell (or respective base station entity) chosen in dependency of especially the signal strength and/or signal quality of the different radio signals received by the user equipment, thereby being prioritized according to a ranking) fails, finally.
• RACH random access channel
• the user equipment tries - after an initial failure of accessing the random access channel of the selected target radio cell, i.e. the radio cell being top-ranked based on the signal strength and/or signal quality of the radio signals received by the user equipment - to access the selected/target radio cell, i.e. its random access channel, again (with especially a maximum number of attempts as defined via information obtained from the selected/targeted radio cell, especially distributed or broadcast on the broadcast control channel, BCCH).
• Further attempts to register with the selected or targeted radio cell after an initial failure of the uplink access procedure by an user equipment can involve using a higher transmission power by the user equipment (especially a higher RACH-power value), especially in case power ramping is used. However, if this further attempt fails or even if these further attempts fail as well, a new cell search procedure has to be initiated.
• the cell selection and/or cell reselection procedure is likely to again select the targeted radio cell of the previous connection attempt, which further connection attempt might end with the same result as the preceding one.
• the location of the user equipment is not changed (i.e. the user equipment is not moved), e.g. that the UE is a fixed installed (LTE) router, the subscriber will possibly not get any network access at all which can have serious drawbacks that might prove costly to the operator of the public land mobile network.
• LTE fixed installed
• An object of the present invention is to provide a method for an improved cell selection and/or cell reselection handling by an user equipment that is trying to camp on a radio cell of a public land mobile network in order to get connected that avoids the drawbacks of the prior art and provides network connectivity and customer service even in situations of problematic radio conditions and/or constellations under which the behaviour of current user equipments can result in not obtaining network connectivity at all.
• the object of the present invention is achieved by a method for an improved cell selection and/or cell reselection handling by an user equipment that is trying to camp on a radio cell of a public land mobile network, wherein the public land mobile network comprises at least a first radio cell with a first base station entity and a second radio cell with a second base station entity, the improved cell selection and/or cell reselection handling being related to an uplink access procedure in dependency of attempts, by the user equipment, to get connected with the public land mobile network using a random access channel of the first base station entity and/or of the second base station entity, wherein the method comprises the following steps:
• the cell selection and/or cell reselection procedure is performed by the user equipment, leading to the result that both the first radio cell and the second radio cell fulfill a cell selection criterion, wherein the first radio cell is prioritized with regard to the second radio cell,
• the user equipment tries to get connected with the public land mobile network using the random access channel of the first base station entity which fails,
• a modified cell selection and/or cell reselection procedure is performed by the user equipment, wherein - despite unchanged radio conditions regarding the first base station entity, the second base station entity, and the user equipment - the user equipment tries to get connected with the public land mobile network using a random access channel of the second base station entity.
• the method according to the present invention allows the user equipment - by using the modified cell selection and/or cell reselection procedure proposed - to leave (temporarily) the targeted cell (determined by the user equipment as a result of the cell selection and/or cell reselection and/or cell reselection process in idle mode) on which the user equipment is camped, in case that an access attempt (i.e. the uplink access attempt on the random access channel) with respect to this cell has not been successful either once or after a defined number of such attempts.
• the proposed method is applicable to any cellular radio network technology, e.g. GSM, UMTS, but aims to provide improvements especially in E-UTRAN (LTE).
• the modified cell selection and/or cell reselection procedure such that the targeted radio cell, top-ranked based on the unmodified cell selection and/or cell reselection procedure, will be treated by the user equipment - at least temporally - in a manner such that the user equipment reduces the priority (or the ranking) of that initially targeted radio cell, i.e. the user equipment makes the originally (by applying the unmodified cell selection and/or reselection procedure) top-ranked cell "artificially" worse (in the ranking or prioritization, i.e.
• the user equipment de-prioritizes that radio cell) than it is (originally, according to the unmodified cell selection and/or reselection procedure) such that, based on the modified ranking or prioritization of the available radio cells, a cell selection and/or cell reselection to a neighboring cell is triggered where access is (at least potentially) possible.
• mobility i.e. cell selection and/or reselection of the user equipment
• mobility is controlled by the user equipment, especially based on measurements conducted by the user equipments about the signal strength and/or signal quality of radio signals, especially the broadcast control channel, received from different base station entities in the vicinity of the current position of the user equipment.
• the user equipment determines whether the radio signal received from a base station entity fulfills the so-called S-criterion or cell selection criterion.
• the radio signals of a plurality of base station entities in one or a plurality of frequencies and/or frequency bands and/or using one or a plurality of different radio access technologies
• the radio signals of a plurality of base station entities in one or a plurality of frequencies and/or frequency bands and/or using one or a plurality of different radio access technologies
• the user equipment has to decide which one of a plurality of suitable base station entities should be the targeted base station entity.
• the user equipment attempts to connect with the public land mobile network using one specific of the suitable base station entities; the one specific (or targeted) base station entity being determined based on the current radio environment of the user equipment and being top-ranked (of all suitable base station entities).
• the top-ranked base station entity is also called the first base station entity and another suitable (but initially not top-ranked) base station entity is also called the second base station entity.
• the inventive method proposes - i.e. in a situation after initially having performed, in a first step, the cell selection and/or cell reselection procedure in unmodified form (i.e.
• the user equipment which leads to the result that both the first radio cell and the second radio cell fulfill the cell selection criterion but the first radio cell being prioritized (or top-ranked or higher-ranked) with regard to the second radio cell
• unsuccessfully trying, in a second step to get connected with the public land mobile network using the random access channel of the first base station entity - to apply the modified cell selection and/or cell reselection procedure such that (despite unchanged radio conditions regarding the first base station entity, the second base station entity, and the user equipment) the attempt to access the random access channel is directed to the second base station entity instead of the first base station entity.
• the first base station entity is de-prioritized or penalized during the modified cell selection and/or cell reselection procedure according to the present invention.
• the scenario can also be applied to the second base station entity, i.e. in case that an attempt to access the random access channel of the second base station entity is (once or repeatedly) not successful, also the second base station entity might be de- prioritized (to the profit of a further base station entity / third base station entity).
• the first and second cells are typically neighboring cells having an at least partly overlapping radio coverage area or at least a geographical area in common where the broadcast radio signals can be received by user equipments.
• Neigboring cells are cells in close proximity with each other, either on the same frequency or the same frequency band (of the same radio access technology) or on a different frequency.
• the modified cell selection and/or cell reselection procedure is conducted by the user equipment applying a penalty information with respect to the first radio cell, the application of the penalty information with respect to the first radio cell resulting - at least potentially - in a lower priority (or rank) of the first radio cell compared to the priority (or rank) of the second radio cell.
• the penalty information comprises an offset information, wherein at least one of the following values:
• the penalty information can also refer to a relative modification - i.e. for example a multiplication by 90% or by 80% or the like - of the measured value of the signal strength of the first base station entity or the first cell.
• the penalty information can also lead to a complete exclusion of the first radio cell from the cell selection and/or cell reselection procedure.
• the penalty information comprises a penalty related timer information, wherein the offset information of the penalty information is applied, when conducting modified cell selection and/or cell reselection procedure, with respect to the first radio cell during a penalty time interval of the length indicated by the penalty related timer information, the penalty time interval starting after the failure, in the second step, of the user equipment trying to get connected with the public land mobile network using the random access channel of the first base station entity.
• the cell selection and/or cell reselection procedure is conducted by the user equipment without applying the penalty information with respect to the first radio cell.
• the modified cell selection and/or reselection procedure is applied as seldom as possible, and preferably in view to reduce occurrences of user equipments that are unable to be connected to the public land mobile network based on the unmodified cell selection and/or reselection procedure.
• the penalty information is transmitted by the first base station entity to the user equipment, preferably on a broadcast channel.
• the penalty information can differ from one base station entity (or radio cell) to another.
• the penalty information is stored in the user equipment, preferably in a firmware-associated memory of the user equipment.
• the present invention also relates to a public land mobile network for an improved cell selection and/or cell reselection handling by an user equipment that is trying to camp on a radio cell of a public land mobile network
• the public land mobile network comprises at least a first radio cell with a first base station entity and a second radio cell with a second base station entity
• the improved cell selection and/or cell reselection handling being related to an uplink access procedure in dependency of attempts, by the user equipment, to get connected with the public land mobile network using a random access channel of the first base station entity and/or of the second base station entity
• the public land mobile network is configured such that a penalty information with respect to at least the first radio cell is transmitted to the user equipment, wherein the penalty information causes the user equipment to apply a modified cell selection and/or cell reselection procedure in case that:
• the modified cell selection and/or cell reselection procedure results - despite unchanged radio conditions regarding the first base station entity, the second base station entity, and the user equipment - in the user equipment trying to get connected with the public land mobile network using a random access channel of the second base station entity.
• the present invention relates to an user equipment for an improved cell selection and/or cell reselection handling in case that the user equipment tries to camp on a radio cell of a public land mobile network
• the public land mobile network comprises at least a first radio cell with a first base station entity and a second radio cell with a second base station entity
• the improved cell selection and/or cell reselection handling being related to an uplink access procedure in dependency of attempts, by the user equipment, to get connected with the public land mobile network using a random access channel of the first base station entity and/or of the second base station entity
• the user equipment is configured such that a modified cell selection and/or cell reselection procedure is applied by the user equipment in case that: - a previous cell selection and/or cell reselection procedure has been performed by the user equipment, leading to the result that both the first radio cell and the
• the modified cell selection and/or cell reselection procedure results - despite unchanged radio conditions regarding the first base station entity, the second base station entity, and the user equipment - in the user equipment trying to get connected with the public land mobile network using a random access channel of the second base station entity.
• the penalty information is transmitted by at least the first base station entity to the user equipment, preferably on a broadcast channel, and/or
• the penalty information is stored in the user equipment, preferably in a firmware- associated memory of the user equipment.
• the present invention relates to a program comprising a computer readable program code which, when executed on a computer or on an user equipment, causes the computer or the user equipment to perform the inventive method.
• the present invention also relates to computer program product for using a core network of a telecommunications network, the computer program product comprising a computer program stored on a storage medium, the computer program comprising program code which, when executed on a computer or on an user equipment, causes the computer or the user equipment to perform the inventive method.
• Figure 1 schematically illustrates an example of a telecommunications network, comprising a core network, a radio access network, an user equipment, and a first and second radio cell.
• a public land mobile network 100 i.e. mobile communication network 100
• the public land mobile network 100 comprises a radio access network 1 10 and a core network 120.
• the public land mobile network 100 is a cellular telecommunications network comprising a plurality of network cells or radio cells, three of which are represented in Figure 1 by means of a solid line and reference signs 1 1 , 12, respectively.
• each of the radio cells 1 1 , 12 is produced by or corresponds to a base station entity.
• Two base station entities 1 1 1 , 121 are represented in Figure 1 .
• In the public land mobile network 100 typically a plurality of user equipments are camping on the public land mobile network 100 within the network cells 1 1 , 12, i.e.
• the base station entitiesi 1 1 , 121 are typically a base station, e.g. BTS (base transceiver station), NodeB or an eNodeB base station.
• BTS base transceiver station
• NodeB base transceiver station
• eNodeB eNodeB base station
• the radio cells 1 1 , 12 typically overlap. Furthermore, overlap of the radio cells 1 1 , 12 is provided to ensure coverage of a certain geographical area not only with respect of one radio access technology but with respect to a plurality of radio access technologies, hereinafter also called different layers of radio coverage.
• Such an network architecture creates a multi-RAT (or multilayer) and/or multi-frequency radio environment in the public land mobile network 100, where an user equipment 20, represented exemplarily in Figure 1 , is located such that it is able to have radio coverage with respect to different radio access technologies and/or with respect to different frequencies or frequency bands of one radio access technology or of different radio access technologies such as GSM (Global System of Mobile communications), GPRS (General Packet Radio System), UMTS (Universal Mobile Telecommunications System), EPS/LTE (Evolved Packet System / Long Term Evolution). Therefore, the user equipment 20 typically has a plurality of possibilities to be connected to the public land mobile network 100 which is
• the first base station entity 1 1 1 or first radio cell 1 1 is assumed to provide the strongest/best radio signal for the user equipment 20 (compared with the second base station entity 121 (or second radio cell 12); this can even be realized in case that the first base station entity 1 1 1 is farther away from the user equipment 20 than the second base station entity.
• the first base station entity 1 1 1 is sufficiently spaced from the user equipment 20, then the user equipment might be unable to transmit a correctly timed random access request to first base station entity 1 1 1 .
• the first base station entity 1 1 1 would still provide the strongest radio signal and the user equipment is incited not to switch to the second base station entity 121 , i.e. the user equipment 20 could be trapped in an infinity loop of still further requests but no successful result.
• the penalty value can be a configurable offset in dB (e.g. 5 dB or 10 dB or 15 dB or 20 dB or 25 dB) or - alternatively - a special value representing the complete exclusion of the so marked cell (first radio cell 1 1 ) within the following cell selection process or plurality of cell selection processes.
• the penalty information is broadcast to the user equipment via the broadcast control channel (e.g. using System Information Block 3 or 4 in a cellular network using the UTRAN standard [3GPP TS 25.331 ] or System Information Block 3 using an E-UTRAN standard [3GPP TS 36.331 ]) and can be configured in a cell-individual manner.
• the penalty information can be fixed coded in a memory of the user equipment, especially in a firmware memory of the user equipment.
• the penalty information shall be applicable in both the cell-selection methods or procedures according to the Basic Biasing as well as according to the Absolute Priorities method.
• the penalty information shall be considered as long as the penalty related timer is not expired and shall finally exclude or worsen the marked cell from/within the newly started selection process.
• This penalty- setting procedure is not limited to a single cell, which means that if also the next uplink- access to an other cell (e.g. to the second radio cell 12) fails, this second radio cell 12 and the first radio cell 1 1 have to be de-prioritized (or even excluded) from the next run of the cell selection and/or cell reselection process as long as their individual timers are not expired.
• a further option according to the present invention includes that as long as the next failed cell is from the same frequency band and radio access technology as the marked cell(s) as before, also their penalty related timer (or penalty time intervals) have to be restarted.
• Still a further option according to the present invention includes that the complete list of cells with penalties shall not be permanently stored. This means that, e.g. after a switch off or reset of the user equipment, the list is emptied.
• the exclusion of the first radio cell 1 1 shall not be permanent, because it might be that the radio conditions, network parameters etc. are changed within the next cell selection cycle. Therefore it is proposed to solve this exclusion with support of a configurable time interval (indicated by the penalty timer information), e.g. 3 minutes.
• This time interval might be a fixed defined value in the 3GPP specifications or can be a configurable parameter broadcasted to the user equipment using the broadcast control channel of the first and/or second radio cell 1 1 , 12. or can be fixedly coded in the firmware of the user equipment.
• the cell shall be not taken into account within the next cell selection process(es) or an extra offset [in dB] shall be added.
• Excluded cells can be stored together with time stamps and positions of the user equipment (if available) from the failed network access as part of the MDT-process and transmitted to the public land mobile network after a successful access has been performed.
• the cell access to a marked cell is successful (e.g. the user equipment moves into significant better radio conditions), then the offset is be removed.
• the proposed method comprises especially the following steps:
• the user equipment performs the following steps
• the penalty offset can be removed from the list of cells with penalties

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